1. Field of Invention
The field of the present invention relates in general to wireless local area networks including wireless access points (WAP) and wireless stations and sounding methods therefore.
2. Description of the Related Art
Home and office networks, a.k.a. wireless local area networks (WLAN) are established using a device called a Wireless Access Point (WAP). The WAP may include a router. The WAP wirelessly couples all the devices of the home network. e.g. wireless stations such as: computers, printers, televisions, digital video (DVD) players, security cameras and smoke detectors to one another and to the Cable or Subscriber Line through which Internet, video, and television is delivered to the home. Most WAPs implement the IEEE 802.11 standard which is a contention based standard for handling communications among multiple competing devices for a shared wireless communication medium on a selected one of a plurality of communication channels. The frequency range of each communication channel is specified in the corresponding one of the IEEE 802.11 protocols being implemented, e.g. “a”, “b”, “g”, “n”, “ac”, “ad”. Communications follow a hub and spoke model with a WAP at the hub and the spokes corresponding to the wireless links to each ‘client’ device.
After selection of a single communication channel for the associated home network, access to the shared communication channel relies on a multiple access methodology identified as Collision Sense Multiple Access (CSMA). CSMA is a distributed random access methodology for sharing a single communication medium, by having a contending communication link back off and retry access a prospective collision on the wireless medium is detected, i.e. if the wireless medium is in use.
Communications on the single communication medium are identified as “simplex” meaning, one communication stream from a single source node to one or more target nodes at one time, with all remaining nodes capable of “listening” to the subject transmission. Starting with the IEEE 802.1 ac standard and specifically ‘Wave 2’ thereof, discrete communications to more than one target node at the same time may take place using what is called Multi-User (MU) multiple-input multiple-output (MIMO) capability of the WAP. MU capabilities were added to the standard to enable the WAP to communicate with multiple single antenna single stream devices concurrently, thereby increasing the time available for discrete MIMO video links to wireless HDTVs, computers tablets and other high throughput wireless devices the communication capabilities of which rival those of the WAP. The IEEE 802.11ax standard integrates orthogonal frequency division multiple access (OFDMA) into the WAP or stations capabilities. OFDMA allows a WAP to communicate concurrently on a downlink with multiple stations, on discrete frequency ranges, identified as resource units.
Increasingly dense deployments of WAP's and stations make new demands on the wireless local area network (WLAN). What is needed are improved methods for wireless communication between the WAP and its associated stations on the WLAN.